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For Fe3+(aq) + SCN-(aq) -> [Fe(SCN)]2+(aq) at equilibrium, what happens if a little more aqueous FeCl3 is added?

1. The forward reaction is favoured and the red colour deepens
2. The backward reaction is favoured and the red colour fades
3. The solution becomes colourless
4. No change occurs

Correct answer: The forward reaction is favoured and the red colour deepens

Solution

Increasing Fe3+ concentration drives the equilibrium forward, producing more of the red [Fe(SCN)]2+ complex, so the colour intensifies.

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